PLA Jams...all the time

I've got a bit of a conundrum. I have printed with the stock Ultimaker PLA, ColorFabbXT and NGen and now I am using MatterHackers Pro PLA and I have noticed a trend, The PLA jams but I can remove it from the print bed while the XT/NGen has never jammed but wrecks my glass build plate upon removal.

I like PLA because it doesn't cost me a $35 piece of glass every couple of prints and it prints well enough when it works but very frequently I get a partially jammed nozzle and every once in a while it stops entirely. When I get a partial jam I get under extrusion of my layers and a very weak print and of course a complete jam causes it to stop dead on that layer. I have tried the recommended 'Atomic method' as suggested by ultimaker but this ProPLA seems to be too brittle to get a good clean pull to clean out the nozzle and the jams seem to be getting more frequent. Is there anyone else that is having that many issues with partial jams and complete blockages and if so what have you done to fix this issue? I've heard that if you set the temperature too high you can carbonize some material to the internals of the nozzle and cause a partial jam, so I have stuck to keeping the temperature as close to the manufactures recommendations as possible. I've never really messed with the extrusion multiplier or the filament diameter, I've always run name brand ("good") material and assumed it to be in good tolerance.

I would recommend playing with the temperature. For Pro PLA, you should definitely go above 195 C. Our recommended temperature is 210 C. You should be safe to experiment up to 220 C. PLA does carbonize, however this is only an issue if you let it sit for an extended period of time. Do not let the PLA sit with the heat on for more than about 15 minutes without extruding or printing.

PLA is not a good material for doing cold pulls (the atomic method). The best material for that is Nylon.

If you want to protect your glass from the XT, try printing on blue painter's tape. The bottoms surface will not come out as shiny, but it will stick well and also be fairly easy to remove.

@AReed030188 as unlimitedbacon said 195c sounds awful low but also the bed should be around 60 Several things can cause jams so more setup info is needed IE have made any mods to your ultimaker? going on that its all stock its not much different from my custom built Bowden feed nozzle diameter so lets touch on the possible causes of a filament jam on this setup

in testing i got these very frequently here some steps took to solve the issue (since about 20ish prints no more jams)

1. Is the cooling fan for the heat break activating from time the hot end starts to heat up or from looks of ultimaker design large heatsink? (my case i altered the marlin firmware to turn it on when ever the hot end is 50c or above.)

2. is your first layer being squashed against the bed?

3. Temp and first layer height pulled right from colorfab's sight on XT and ultimaker2

ULTIMAKER 2 – SPEED AND TEMPERATURE SETTINGS

LAYER HEIGHT (MM)

SPEED (MM/S)

TEMPERATURE (C)

BUILD PLATE TEMPERATURE (C)

0.2

50

240-245

70

0.1

50 - 70

235-240

70

4. lastly is the bowden extruder set to tight and digging into the filament? (cause filament to jam in the hot end) if it has been in past it will scour your ptfe tube and cause jamming

I suspect it might be the latter, I removed the bowden tube to do a pull and I found PLA dust all over the cool side of the extruder (resting on top of the PTFE heat break). I have't been able to tinker with it in a few days (very busy wrapping up a FIRST Robot for competition) but I plan on blowing that mess out of there and inspecting the extruder gear for debris and turning down the tension. I'll get back to you all in a few days and let you know how it goes.

I have also seen issue number two from time to time and I'm still not 100% on how the "CNC" picks up on the Z zero position when leveling the bed. I've found my best results are still obtained when using the little plastic/paper card that came with the machine. Any tips or tricks on how to get this right otherwise?

finding filament debris is a good sign well in that we can see a cause the extruder grinding threw the filament. as for the z height it is set when the printer z homes and touches the endstop switch giving it Z 0 POS a sheep of standard print paper is best to set the bed to hot end distance.

home printer usual front left corner, this sets it to 0 then adjust bed corner till it is just close enough to add a little friction to the paper sliding under then move hodent to other 4 and repeat adjusting bed till its same height.

Well I believe I have solved the issue with grinding the filament by adjusting the tension screw but I am still having under extrusion problems periodically. I checked the feeder and the hot end after this print and I didn't find any loose filament dust and the bite into the part is minimal at best but I am still getting periodic weak layers leading to weak or broken parts.

ok right off the bat lets check extrusion caliper or decent ruler manually heat up hotend to current filament temperature then remove the bowden tube pull slowly the tip of filament will be multon. next cut the filament off flush to the end of tube.

with hotend still at temp you should be able to use manual control and extrude a given length. extrude 100m then measure you should have a 100m length of filament stick out the end of the bowden tube let know if under or over and by how much.

if havent altered any settings it should be very close but its one of easy items to check.